Chapter 5 - The Impact of Inflammation on Brain Function and Behavior in Rodent Models of Affective Disorders

Abstract

Major depressive disorder (MDD) is a common psychiatric illness and has been identified as the leading cause of disability worldwide, by the World Health Organization. Anxiety disorders are also extremely common and often poorly treated. This makes it imperative to gain better insights into biological mechanisms mediating the pathogenesis of MDD and anxiety disorders. Recent years have witnessed increasing evidence supporting the involvement of inflammatory mechanisms in the pathophysiology of such affective disorders, thus paving the way for the field of psychoneuroimmunology. In this review, we highlight the effect of stress-induced cytokines on affective behavioral abnormalities, targeting some of the mechanisms involved in mood regulation, such as altered serotonin signaling; activation of the kynurenine pathway leading to serotonin clearance and accumulation of kynurenine metabolites; altered hippocampal neurogenesis, with a special focus on the role played by gut microbiome; and sex differences in mediating the inflammatory phenotype associated with behavioral alterations in rodent models.